\section*{Es. 2}

Keeping in mind the first exercise

\begin{enumerate}

    \item separate the program in multiple files, in a modular way, so that
    code usability is improved. Hint: group all implementations in a source
    file, add a correspondent header file and keep the main in a third file.

    \item repeat the last point of the first exercise.

    \item knowing that the exact solution for the previous point is
    $x=\sqrt{0.5}$, modify the code in order to save the distance between the
    current approximate solution and previous approximate solution in a file.
    Plot the solution with \texttt{gnuplot}. Comment the results using the
    theory.

\end{enumerate}
